从字符串文字中删除逗号

Question

I want to concatenate string with array Item.

I tried following.

 const str = "I have following things:" const arr = ["chair", "table", "bed"]; const tootlTipText = `${str} ${arr.map(item => `- ${item} \n`)}`; console.log(tootlTipText);

It display, in between. I tried to find and can't find what is the issue.

Answer 1

The problem is that by default, when you convert an array to a string, it's done as though you called .join(",") . To avoid that, call join yourself with whatever separator you want, perhaps "" :

 const str = "I have following things:" const arr = ["chair", "table", "bed"]; const tootlTipText = `${str} ${arr.map(item => `- ${item} \n`).join("")}`; console.log(tootlTipText);

Alternatively, you could use a simple loop with string concatenation:

 const str = "I have following things:" const arr = ["chair", "table", "bed"]; let tootlTipText = `${str}\n`; for (const item of arr) { tootlTipText += `- ${item} \n`; } console.log(tootlTipText);

Some folks would also use reduce for this; personally I don't like reduce except in functional programming with predefined, tested reducers, but:

 const str = "I have following things:" const arr = ["chair", "table", "bed"]; const tootlTipText = arr.reduce( (str, item) => str + `- ${item} \n`, `${str}\n` ); console.log(tootlTipText);

Answer 2

Array.prototype.map() returns an array. It should be converted to string.

const tootlTipText = `${str}
    ${arr.map(item => `- ${item} \n`).join('')}`;